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`To ALL WHOM 1T MAY ooNcEsN:

, @n'trntatrsgstmt @Hirer Letters Patent No. 74,490, dated Febmary 1868.

IMPROVEMENT IN SCREW-DRIVERS AND BORING-TOOL.

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Be it known that I, JASON A. BIDWELL, of East Boston, in the countyV of Suffolk, State of Massachusettm have invented a Combined Screw-Driver, Boring-Tool, and Countersnk; and I do hereby declare the following to be a full, clear, and exact description thereof, reference being had to the accompanying drawings, making part of this speoieatiom'in which-.- f

' Figure 1 is a perspective view of` the `improved tool;

Figure 2 is an end view of-the same,

Figures 3 and 4 illustrate the manner of using the tool. p

Similar letters of reference indicate corresponding parts in the several figures. p

The object of this invention is to produce a tool that shall practically serve for boring and counter-sinking diiferent depths into wood,'and also for inserting screws into wood.- TheI instrumen/t which I shall describe is designed particularly for driving screws which are constructed with central tapering holes in their heads for receiving a rectangular tapering screw-driver.` p

To enable( others skilled in the art v tdillgderstand my invention, Iwill describe itsconstruction and operation.

A is thehandle of the instrument, and B the staff, which is secured therein in any suitable manner. The end'of this staff furthest from the handle is reduced Vsc as toform a square shank or stem, a, the sides of which are parallel to each other, for the' purpose of receiving a countersink, b, and admitting of the endwise adjustment thereof, as will be hereinafter explained, This square shank a terminates in atapering rectangular bit, c, which is grooved or scored, as shown at e, Aand constructed with four radial Asharp cuttng-edgeathat are produced by rst forming a pyramidal point, and then grooving the plane surfaces thereof. This bit c presents four right angles to the sides of the holefin the screw C, shown in g. 4, and, by its being made' tapering., it

vwedges itself tightly in' said hole f, and thus serves as a screw-driver for the perforated headwood-screws.

` The sharp bevelled edges on the end of the* bit c, 'together with the scores orgrooves e`in`it's four sides, adapt it to serve an excellent purpose as a boring-tool for making holes in wood. The scores e in .said bit are designed for allowing the free upward escape of the chips fromthe cutting-edges as the bit enters the wood,

so that these edges shallinot become" clogged.

g The countersink b, which is 'upon thev square shanlca, is a 4cylindrical piece of metal, having bcvclled cutting-edges formed upon one end, of api-oper description for countersinking'in wood. -There' are four cutting-edges on the countersink, shown in the drawings, which edges correspond to and are arrangedin the middle of the four sides of the shank, as shown infigs. 2 and 3.A This countersink is applied to the` shank, so that it can be adjusted and set, by means of the screw'd, at any desired distance from the'end ofbit c, accordinglto the depth of hole whicht is desired to bore. 4 i

It will thus be seen that the bit c is'adapted to serve as a screw-driver and boring-tool, and also that this hit is provided witha. reamer for teaming theholes bored in the wood ready for receiving thc screws. Y While I prefer to have the, countersink bit I adjustable upon its shank or bit,I do not confino my invention to this construction, as it may be formed on the shank or Vstaff of the tool, so as not to be adjustable. In this case the ftool is adapted for boring a. hole, and ccnntersinking it, .of agivcnl'length only while in the former case the bit can be caused to penetrate different depths in wood, and countersink th holes. Y

While this improved toolis designed particularly to be used with perforated head-screws, it may be employed successfuliy for boring and -countersinking holes for receiving the common slit-head screws to b e inserted with the fiat-bit screw-driver.

Having described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. 'The construction of a screw-driver, which is adapted for driving perforated head-screws, with cuttingedges formed on a pyramidal point, in combination with scores or grooves e for conducting out ,of the hole the chips or dust, while in the act of boring, substantially as described. p 2. s a new and improved article of manufacture, a'tOOl having a rectangular ltapering point, c, a rectanguiar straight shank, a, and an .adjustable countersink, b, said tool being adapted to serve the threefold purpose of afscrew-driver, a boring-tool, and a counter-sink, as herein setl forth.

JASON A. ,BIDWELL.

Witnesses:

WM. B. W. Hamann, SrnPnnN A. Cooxn, Jr. 

